New headlamp assembly or aftermarket lights?

Assuming that you mean Xenon plasma and not filament: They won't focus the same since the reflectors were not designed for Xenon HID's. Since they are bluish and not yellow, they won't go as far, however definition will be sharper. They will scatter more and annoy other drivers. You and your car would be impounded in Texas with a total cost of $5,000 in attorney fees and fines.

I assume Plasma if that's the norm - they have a brief 'power up' time

- when I turn them on they have to warm up or otherwise power up to get brighter. They had a little ballast that was installed along with each one if that helps with what I have.

That's why I asked if there's a reflector I should purchase :)

They're the closest to white without being blue. I forgot the light rating. The next step up was 'blue' these are white.

They haven't annoyed anyone.

This is California. They are perfectly legal.

Those are the good ones. Check into reflectors. The xenon arc is usually not in the same place as a filament so it throws the focus off. Blue would have worse distance and scatter since it has an even shorter wavelength. I prefer the old yellow bulbs with longer wavelength due to wanting to light a good distance away. My friend's Accura has Xenon HIDS. They are nice but I like my old yellowish bulbs better. You can have xenon in Texas as long as they are factory. Its just another way for the legal system to get your money if you get caught making changes to oem.

So back to my original question, what's a good bet or better idea, HID reflectors, or aftermarket spot / headlamps that mount on the grill?

Sorry. I don't know the answer since after market lights can't be used on Texas highways. They are ok for off-road use though. However, here I would go with relectors to keep the bears at bay.

My 2 cents is to use whatever lightbulbs can be properly focused so that they don't blind other drivers and illuminate the road properly for you. And are legal, of course. So, these points are what you need to find out!

Being on the other end of someone else's mis-focused strong headlights is a real bitch at night. You know that.

Perhaps having a friendly chat with a couple of cops will help, and calling around the DMV could point you in the right direction. I once had a 1/2 hour conversation with someone at my state's smog HQ. The man gave me an excellent overview of how our cars' computers work and where to go to find out Hyundai's "secret" drive cycles. Note: the place where I found them was not Hyundai! And getting my hands on those routines helped me pass my smog test. Sometimes people who work for government can be really helpful.

This is something I'm also interested in, but haven't researched thoroughly yet. Seems to me part of the equation is cost - what would external headlamps that mount on your grill cost Vs replacement HID reflectors? Unless there's a big difference I'd go with the reflectors because it seems to me they would be more stable (in terms of "aiming") and not vulnerable to damage compared with externally mounted lights. There's also the issue of installation - with external lights you have additional wiring, switches, maybe holes drilled, etc, while replacement reflectors just "drop in" without disturbing anything. Based on what I've seen with after-market alarm systems and stereos the car is always a little worse for wear after these procedures.